Sensitivity of Boana pulchella (Anura: Hylidae) Tadpoles to Environmentally Relevant Concentrations of Chlorpyrifos: Effects at the Individual and Biochemical Levels

Abstract

We report sublethal effects of environmentally relevant concentrations of chlorpyrifos at the individual (swimming alterations) and biochemical (esterase activities and antioxidant enzymes) levels in the Montevideo tree frog Boana pulchella larvae. The 50% lethal concentration at 96 h (LC50‐96h) for chlorpyrifos in stage‐29 B. pulchella tadpoles was 0.98 mg/L, which was close to the 65th percentile of published anuran species sensitivity. In B. pulchella, chlorpyrifos disrupted biochemical processes: tadpoles showed a significant inhibition of esterase activity and a significant induction of antioxidant enzymes, indicating a response to an environmental challenge causing oxidative stress. Using principal components analysis, we could associate chlorpyrifos reduction in esterase activity with swimming alterations at 0.5 mg/L of the toxicant. The biochemical biomarkers reported in the present study respond at levels 20 times lower than the LC50‐96h and were associated with a biologically important response—swimming behavior. The link of responses across different levels of biological organization was demonstrated. The species is suitable as a model for ecotoxicological studies at different levels, including the individual and biochemical levels, and may be considered a good reference organism in environmental control programs. Environ Toxicol Chem 2020;39:834–841. © 2020 SETAC

Lethal and sublethal effects of the natural and healthy spinosad-based formulation Tracer™ on tadpoles of two neotropical species

“…The differential response of both species exposed to other insecticides is consistent with the results reported here, being B. pulchella more sensitive than R. arenarum when considering lethal effects of endosulfan (Agostini et al 2009;Svartz et al 2014), chlorpyrifos (Liendro et al 2015;Barreto et al 2020), cypermethrin (Agostini et al 2010;Svartz et al 2016), andpirimicarb (Vera Candioti et al 2010;Natale et al 2018). Although R. arenarum is the most frequently used test species in Argentina, reported data indicate that it is not the most sensitive one.…”

Effects of chlorpyrifos on early development and anti-predator behavior of agile frogs

“…in 2003, 4000-4900 tons of chlorpyrifos were used in the US, while only 1226 tons in European Union (EUROSTAT, 2007;Grube et al, 2006). Studies that used similar concentrations as we did in our experiment also found no significant effects on these variables (Barreto et al, 2020;Bernabò et al, 2011a;Bidwell, 2008, 2006). This highlights the importance of studying the full range of environmentally relevant concentrations in ecotoxicology.…”

“…In our experiment, the lack of significant effects of chlorpyrifos on survival and development were probably due to the use of relatively low concentrations. The majority of previous studies applied much higher concentrations (Barreto et al, 2020;Bernabò et al, 2011aBernabò et al, , 2011bDe Arcaute et al, 2012;Kendall, 2003, 2002;Rutkoski et al, 2020;Silva et al, 2020;Bidwell, 2008, 2006), although some of these concentrations were referred to as ecologically relevant (Barreto et al, 2020;Bernabò et al, 2011b;Widder and Bidwell, 2008). In these earlier experiments, the applied concentrations were based on surveys from the United States, Canada and South America, where this active ingredient was used in much higher amounts than in Europe e.g.…”

Effect of Acute Toxicity of Commercial Organophosphate Insecticide Based on Chlorpyrifos on Fejervarya limnocharis Tadpoles (Anura: Dicroglossidae)

“…The range of LC50 values at 96 th hours (2.2 -4.2 µg/L) was lower than the results of studies in other species but was close to the value found of the research on the Hoplobatrachus tigerimus (19 µg/L) [35]. It is very different from the LC50 value of Physalaemus gracilis (893.59 µg/L [36]), Rhinella fernandezea (151 µg/L [37]), Bufo gargarizans (800 µg/L [19]) and Anaxyrus americanos (1000 µg/L [38]), Rana dalmatica, and Duttaprinus melanostictus (5,74 mg/L and 5.9 mg/L [39]), Physalaemus ragilla and Rana boylii (365µg/L and 108.7µg/L [39]) and Boana pulchella (0.98 mg/L [40]) tadpoles. A higher LC50 value indicates a lower level of toxicity because higher concentrations are required to kill 50% of experimental animals [41].…”